Charles e



I (No Model.)

0. E. SORIBNER.

TELEPHONE EXCHANGE SYSTEM. Patented Dec. 29, 1896.

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LII

UNITED STATES PATENT @FFICE.

CHARLES E. SCRIBNER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE ESTERN ELECTRIC COMPANY, OF SAME PLACE.

TELEPHONE-EXCHANGE SYSTEM.

SPECIFICATION forming part of Letters Patent N 0. 574,221, dated December 29, 1896. Application filed June 6,1894. Serial No. 513,720- (No model.)

To all whom it may concern.-

Be it known that I, CHARLES E. ScRIBNER, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Telephone-Exchange Systems, (Case No. 357,) of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to signaling apparatus of telephone-exchange systems. Its object is to transmit signals automatically from a substation to the central station of the system to notify the attendant at the central station that a connection is desired or to instruct her to break a connection already established, the transmission of the signals being controlled automatically in the use of the telephone.

As is well known, in the ordinary telephoneexchange system each substation is provided with a generator of signaling-current, and suitable annunciators are connected with each line therefrom at the central exchange, adapted to be operated by the generators of signaling-current. A subscriber requiring a connection from his line to some other line of the exchange attracts the attention of the operator at the exchange by rotating his generator and thus operating the individual annunciator connected with his line. When the desired connection is made with the line,'another annunciator, known as the clearingout annunciator, is connected therewith,

' while the first an nu nciator is disconnected or rendered inoperative. Having finished his conversation, the subscriber again rotates his signaling-generator, whereby the second-mentioned annunciator is operated, its signal being understood by the operator to indicate station. To this end I provide a common signaling-battery or source of electric current at the telephoneexchange, grounded at one pole and connected at its other pole through an individual ann unciator with each line-wire 5 5 of the exchange system, and at each substation I arrange switch-contacts controlled by the automatic telephone-switch, adapted to ground the line at the substation when the telephone is removed from the switch-hook and to disconnect it therefrom, as far as continuous currents are con cerned,when the telephone is again replaced upon its switch-hook.

I provide the usual clearing-outannunciator and means for connecting it with the line and for rendering the individual annunciator inoperative when connection is made with the line. The individual annunciator may be of ordinary character, adapted to display its indication when current finds circuit through it; but the clearing-out annunciator is of different type and is arranged to conceal its indication while current exists in its coil and to display the same when such current ceases. Thus when the telephone at a substation is removed from its switch-hook the corresponding line is grounded there, the circuit of the common signaling-battery is closed through the individual annunciator, and the latter gives its signal. Connection is then made with the line in the usual way, whereby the clearing-out annunciator is connected with it and the signalingbatter Y finds circuit through this annunciator also to earth at the substation, retaining the clearing-out annunciator, however, in position to conceal its indicator. WVhen, the conversation having been finished, the telephone is again replaced upon the switch-hook at the substation, the circuit of the common battery through the clearingout annunciator is interrupted and the latter gives its indication.

Itis of course necessary to have some means by which the operator at the exchange may signal to the substation, so .that some form of 5 return-circuit from the substation is required. Ipreferto employ for this purpose a normallyclosed ground branch from the line at the substation, including a proper signaling instrument, as a polarized bell, together with a condenser, a coil of high resistance, or other well-known means for preventing suilieient [low of battery through the line to earth at the substation to operate the annunciator. When the condenser mentioned is employed, the operator at the exchange may be provided with a generator of signaling-current of alternating character, which will find free passage through the condenser and will thus operate the polarized bell.

M y invention is illustrated in the accompanying drawings.

Figure 1 of the drawings represents in perspective view the special clearing-out annunciator which I employ. Fig. 2 is a diagram of the circuits which constitute my invention.

Referring to Fig. 1, the clearing-out annunciator a is seen to comprise the usual tubular magnet Z), having a pivoted armature 1), carrying an arm b provided at its extremity with a catch Z), engaging a shutter 11*. This shutter is pivoted at its lower edge to one side of its center of gravity, so that when released it falls outward and displays a number of other indications upon the face-plate b. The catch 1) is adapted to engage the shutter Z)" only when the armature b is attracted, this being the position in which the annunciator is shown in the drawings. \Vhen the armature is unattractcd, the catch falls and permits the shutter to fall outward.

In Fig. 2 two substa ions are represented, each connected by a line-wire with two springjacks and with an annunciator upon a switch board at a telephoneexchange. Thus the station 0 is provided with a line-wire d, which is connected with a spring-contact c of each of two spring-jacks f and f and with one terminal of an ordinary self-restoring annunciator g. The other terminal of annunciator g is connected through the common signalingbattery 7b to earth. The spring-jacks f and f are assumed to be located upon two different sections '5 and t" of a multiple switchboard, the individual annunciator 9 being upon the section 2". At the substation the line-wire d connects with the lever of a switch-hook 70, one of whose switch-contacts is connected through a polarized bell Z and a condenser on to ground, and the other of whose contacts is connected through a telephone set it to ground. Each spring-jaek, in addition to the line-contact c, has a spring c and a thin1- ble 0 which form the normally-separated terminals of a local circuit including the restoring or resetting magnet of the individual annunciator together with local battery h. The station 1) is provided with similar apparatus and is likewise connected with springjacks q and q and with an annunciator 7' upon the switchboards i and i at the exchange.

The operator at the switchboard has a number of connecting-plugs s and .9. Each of these plugs comprises a central stem 25, terminating in a spherical tip adapted to make connection with line-spring e of a springjack into which the plugmaybe inserted, and a sleeve t, which is formed to cross together the local spring 0' and the thimble e of the springjack. The tips t of two plugs are connected together to form a pair, calling keys u and 1/ being included in the conductor uniting them. These calling-keys are arranged with normal resting-contacts which are connected together, and with alternate contacts which are connected with one terminal of a generator 1) of signaling-current so that by depressing either key the tip of the corresponding plug is connected with the generator. A permanent connection is extended to the lever of listening-key in, whose switch-contact constitutes one terminal of the operators telephone set a:. A clear ing-out annunciator 3 of the kind shown in Fig. 1, is permanently connected in a branch from the conductor uniting the plugs to the common battery h. The magnet of the clearing-out annunciator is constructed to have sufficient self-induction to prevent the shunting of telephonic current to earth through its coil.

The operation of my invention will be readily understood from an inspection of the drawings. In the normal condition of the apparatus at the substation the circuit of battery 71 to ground at the substation is practically open at the condenser m, the telephone being ordinarily upon the switch-hook. hen the telephone is removed from the switch-hook by the subscriber, the circuit is immediately closed from the line through the telephone set a, whereby the annunciator g is caused to release its shutter. The operator at switchboard i, seeing this indication, inserts a plug .9 into the corresponding spring-jack f upon her switchboard, at the same time depressing listening-key to. Her telephone x is thus connected with the telephone n at substation c, and the subscriber is enabled to communicate the order for the desired connection. Vhen the plug 8 was inserted into the jack, the spring 0' and the thimble e of the jack. were crossed together through the sleeve t of the plug, thus closing the local circuit of battery 7t and resetting the indicator of annunciator g. At the same time circuit was completed from battery h, through clearing-out annunciator (1 to the line (Z and thence to earth at the substation, whereby the clearingout annunciator was placed in position to conceal its indication.

Having received the order for connection, the operator tests the line called for, for example, that to station 19, in the usual way, that is, by applying the tip of plug 3 to the thimble e of the spring-jack q of that line to determine whether this thimble is connected with battery h. Having found the line free, the operator inserts the plug 8 fully into the spring-jack q, thereby connecting the lines and 19' together into a continuous circuit. She then depresses the corresponding callingkey, looping generator o into circuit,

the alternating current of this generator finding a free path to earth through the polarized bell Z and the condenser m at station 1).

When the subscribers, having finished their conversation, replace their telephones upon the switch-hooks, the circuit from battery h through the clearing-out annunciator y to earth at the substations is interrupted, and the annunciator permits its shutter to fall, thus indicating to the operator that the lines may be disconnected.

Having thus described my invention, I claim as new and desire to secure by Letters Patent 1. The combination with a telephone-line normally open at a substation, provided with a switch adapted to close a circuit through a telephone there, of an annunciator together with a source of current in the line-circuit at a central station, a connecting-plug for makcator upon the cessation of current through it,and circuit connections completed with the said line when connection is made therewith including said clearing-out annunciator, substantially as described.

2. The combination with a telephone-line normally open as to continuous currents at its substation, having a switch adapted to close the circuit during the use of the telephone, of an annunciator together with a source of current permanently connected with the line at a central station, an electromagnet adapted When excited to conceal the indicator of the line-annunciator, a normally open local circuit including the said electromagnet, a clearing-out annunciator adapted to display its signal upon the cessation of current in it, and means for making connection with the line and simultaneously connecting therewith the said clearing-out annunciator and closing the said local circuit, substantially as described.

In witness whereof I hereunto subscribe my name this 14th day of May, A. D. 1894.

CHARLES E. SORIBNER. 

